Elementary cyclic normal group theory

Click For Summary
SUMMARY

The discussion centers on proving that for a finite group G with a normal subgroup H of finite index m, the element a raised to the power of m (a^m) belongs to H for all elements a in G. The canonical map φ: G → G/H, defined by g ↦ gH, is suggested as a tool to analyze the behavior of a^m. Additionally, it is clarified that the statement "order of a group equals the order of an element" is only true for cyclic groups where the element is a generator.

PREREQUISITES
  • Understanding of group theory concepts, specifically normal subgroups.
  • Familiarity with finite groups and their indices.
  • Knowledge of canonical mappings in group theory.
  • Basic comprehension of cyclic groups and their properties.
NEXT STEPS
  • Study the properties of normal subgroups in group theory.
  • Learn about the canonical map and its implications in quotient groups.
  • Explore the concept of group indices and their significance in finite groups.
  • Investigate cyclic groups and the conditions under which the order of a group equals the order of its elements.
USEFUL FOR

This discussion is beneficial for students of abstract algebra, particularly those studying group theory, as well as educators and researchers looking to deepen their understanding of normal subgroups and cyclic groups.

eileen6a
Messages
18
Reaction score
0

Homework Statement


If G is a finite group and let H be a normal subgroup of G with finite index m=[G:H]. Show that a^m\in H for all a\in G.


Homework Equations


order of a group equal the order of element.


The Attempt at a Solution


no idea.
 
Physics news on Phys.org
Consider the canonical map \phi : G \rightarrow G/H defined by g \mapsto gH. What can you say about \phi(a^m)?

P.S. "order of a group equal the order of element" is false unless the group is cyclic and the element is a generator of the group.
 

Similar threads

  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 1 ·
Replies
1
Views
5K
  • · Replies 3 ·
Replies
3
Views
3K
Replies
3
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K
Replies
5
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K